Retractable ladder

ABSTRACT

A retractable ladder is in the form of a generally U-shaped member adapted for operative use in a vertical position and which may be stored in an inoperative position within the supporting body by lifting the bottom rung or step and pushing the ladder into the body. Optional stops are provided on the ladder for limiting its travel. Optional hand grip means are also provided.

United States Patent [191 Liptak et al.

[111 3,826,337 [451 July 30, 1974 RETRACTABLE LADDER Neil R. Liptak, .loliet; Beno E. Echerd, Washington, both of 111.

Caterpillar Tractor Co., Peoria, 111.

June 28, 1973 US. Cl 182/91, 182/88, 182/92, 280/166 Int. Cl. B60! 3/02 Field of Search 182/90, 91, 92, 88, 228,

182/86, 127; 280/166; 248/DIG. 3

References Cited I UNITED STATES PATENTS Bcnnc 182/91 Seyforth 248/D1G. 3

2,922,557 l/1960 lessen '182/88 3,357,719 12/1967 McCrea.. 182/92 3,498,410 3/1970 Storch 182/206 3,584,704 6/1971 Eckmann 182/90 Primary Examiner- Reinaldo P. Machado Attorney, Agent, or FirmPhillips, Moore, Weissenbe'rger Lempio & Strabala 57] ABSTRACT A retractable ladder is in the form of a generally U- shaped member adapted for operative use in a vertical position and which may be stored in an inoperative position within the supporting body by lifting the bot tom rung or step and pushing the ladder into the body. Optional stops are provided on the ladder for limiting its travel. Optional hand grip means are also provided.

6 Claims, 2 Drawing Figures RETRACTABLE LADDER BACKGROUND OF THE INVENTION DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT I FIG. 1 of the drawing illustrates the subject ladder at This invention relates to a ladder assembly for dispo- 5 shown mounted on a side'support surface in the sition on the side of .a structure having a provision for retraction of the ladder assembly from its operative to a stowed position within the structure. More particularly, this invention is directed to a retractable ladder for use on vehicles such as large earth-moving vehicles.

While the following discussion concerns use on earth-moving vehicles, it is to be understood that such is merely for the sake of convenience. The invention has wider application to other uses where similar requirements are present.

As the size and complexity of large earth-moving machines increase, one problem that is encountered is that of providing easy access to various portions thereof including the drivers station and numerous service areas. In the past, use of permanently fixed ladders on vehicles necessarily within easy reach of the ground support surface has not been satisfactory. This is the case since the bottom portions thereof are usually placed below the normal ground'clearance of the vehicle and therefore in a position to be damaged when the machine is in motion. In attempts to solve this problem, various types of retractable steps have been devised which can be pivoted or lifted out of the way. An example is shown in US. Pat. No. 3,603,429, to Shepherd. Nevertheless, most of these prior art ladders are still subject to being damaged and in some cases can be shaken or jarred loose during vehicle operation.

SUMMARY AND OBJECTS OF THE INVENTION It is therefore the primary object of this invention to provide a ladder assembly that overcomes the abovenoted disadvantages.

It is particularly an object of this invention to provide a ladder which is retractable from its operative position to a stowed position.

It is also an object to provide such a ladder which is simple and inexpensive and is quickly and easily extended and retracted.

form of a scraper, a rear frame portion of which is shown at 11. The ladder is a generally U-shaped member having a pair of parallel, vertical arms 12, 13 joined by a horizontal step portion 14. The'ladder'provides access to a horizontal platform 17 on the rear of the vehicle which isused by an operator when servicing various parts of the vehicle including the engine shown generally at 15.

the ladder are found by having reference to F IG; 2. The

It is a still further object of this invention to provide such a ladder which can be secured to a vehicle with a minimum of alterations.

The invention takes the form of a ladder for disposition on the side of a supporting structure comprising a generally U-shaped member defining a pair of legs and having a hook member formed on each end thereof. The ladder is secured to the side supporting structure such as a vehicle frame by inserting the hook members into a pair of spaced holes therein. The ladder may be stowed or stored by lifting the bottom or stop portion thereof and pushing it into the frame.

Other objects and advantages will become readily apparent to one skilled in the art from having reference to the following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is an over-all isometric view of the invention shown mounted, on the rear portion of earth-moving scraper vehicle} and FIG. 2 is a fragmentary, cross-sectional view of the same taken along lines II-ll in FIG. 1.

ladder 10 may be conveniently formed from metal bar stock. A hook, one of which is shown at 20 is formed at the end of each of the legs of the ladder opposite the horizontal step. The ladder, in turn, is secured to the side support surface such as vehicle frame exterior wall surface 2l by inserting the hook members into apair of spaced holes 22, 23 as best seen in FIG. 1. When the ladder is lowered into operative position as best seen in FIG. 2, the extremities of the hook members which are parallel to the vertical arms contact the inner wall of the side supporting surface to hold the step in place. Optionally, a horizontal spacer block 24 for spacing the arms from the supporting surface can be secured to the frame exterior wall surface 21. Also optionally, and as best seen in FIG. 1, a pair of stops in the form of washers may be fixed to the vertical arms at their juncture with the horizontal step. These stops 25, 26.will contact wall surface 21 when the ladder is in the stored condition, as shown in phantom at 10"in FIG. 2. These stops function both to prevent the ladder from being positioned too far within the frame but'also to prevent twisting when in the stored position.

In operation, the operator merely lifts the ladder'and pushes it into the frame. The weight of the ladder and particularly the arms being at a lower level than the horizontal step, facilitated by having sufficiently large holes, causes it to remain in its stowed position even during rough operation. To remove the stored ladder,

the operator merely grasps the horizontal step 14 and pulls it out of the storage position until the hook contacts the inner frame surface and releases the step whereupon the ladder will pivot downward to its operative position. I

It is to be understood that the foregoing description is merely illustrative of preferred'embocliment of the invention and that the scope of the invention is not to be limited thereto, but is to be determined by the scope of the appended claims.

What is claimed is:

1. In combination a ladder and means defining a side support surface comprising a vehicle frame, said ladder comprising a generally U-shaped member defining a pair of arms joined by a bottom step member, hook members formed on the ends of the arms opposite to the bottom step member, a pair of spaced holes in said vehicle frame and whereby said arms extend through and spaced from said holes, such that the ladder may be moved to a generally vertical operative position parallel to the vehicle frame as well as to an inoperative position-by raising the bottom step and moving the ladder into said vehicle frame and further including a step means in said vehicle frame located between said arms and spaced from said bottom support member when in the operative position.

2. The invention of claim 1 further including stop I members on said arms adjacent the bottom step member.

3. The invention of claim 1 wherein said holes are dimensioned with respect to said arms received therein grip means on said frame for use when mounting said ladder. 

1. In combination a ladder and means defining a side support surface comprising a vehicle frame, said ladder comprising a generally U-shaped member defining a pair of arms joined by a bottom step member, hook members formed on the ends of the arms opposite to the bottom step member, a pair of spaced holes in said vehicle frame and whereby said arms extend through and spaced from said holes, such that the ladder may be moved to a generally vertical operative position parallel to the vehicle frame as well as to an inoperative position by raising the bottom step and moving the ladder into said vehicle frame and further including a step means in said vehicle frame located between said arms and spaced from said bottom support member when in the operative position.
 2. The invention of claim 1 further including stop members on said arms adjacent the bottom step member.
 3. The invention of Claim 1 wherein said holes are dimensioned with respect to said arms received therein so as to allow the arms to position themselves at a lower level than that of the horizontal step when in the inoperative position.
 4. The invention of claim 1 further including a spacer means on said vehicle frame for spacing said arms from said vehicle frame.
 5. The invention of claim 4 wherein said spacer means is a spacer block mounted on said vehicle frame in a location to contact said arms when in the operative position.
 6. The invention of claim 1 further including hand grip means on said frame for use when mounting said ladder. 